Firstly, we research and analyze the realization theory of IPSec in Linux, involved the Netfilter/IPtables in Linux.Just the alternation between it and IPSec realizes IPSec in Linux.

• 首先对IPSec在Linux下的实现原理进行了分析研究，这其中涉及到Linux下的Netfilter/IPtables防火墙子系统，正是它与IPSec的交互使得在Linux下实现IPSec成为现实。